Apparatus for edge-gluing strip elements



Ncv'. 9, 194s.

- P. H. BILHUBER APPARATUS FOR EDGEGLUING STRIP ELEMENTS Filed Sept. 10. 1943 2 Sheets-Sheet 1 177' 7' DR VE) Nov. 9, 1948. .P. H. BILHUBER APPARATUS FOR EDGE-GLUING STRIP ELEMENTS 2 Sheets-Sheet 2 Filed Sept. 10, 1943 HTTORNEY Patented Nov. 9,' 1948 APPARATUS FOR EDGE-GLUING STRIP ELEMENTS Paul H. Bilhuber, Douglas Manor, N. Y., assignor to Steinway & Sons, New York, N. Y., a corporation of New York Application September 10, 1943, Serial No. 501,792

3 Claims. 1

This invention relates to the edge-gluing of strip elements such, for example as lumber-core stock for lumber-core plywood, solid dimension stock for chair seats, solid tops, piano soundboards, etc, and veneers and to the apparatus therefor and relates more particularly to the continuous-feed edge-gluing of elements of the nature aforesaid and to the apparatus therefor.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of processes, steps, instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel steps, methods, procedures, parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Edge-gluing of lumber boards or other strip elements using thermo-setting adhesives, by means of so-called continuous-feed presses is well known. In such operations. the elements issue from the press as a continuous ribbon of elements in edgejoined relationship. In order to "set the adhesive along each "glue line the press is provided with hot plates or surfaces which bear upon and heat the elements as they are intermittently advanced therebetween by strokes of a lever at the feed end of the press. Such presses are characterized by an excess length consequent upon the length of heating surface required for a favorable rate of production of a ribbon or panel having glue joints of strength adequate to permit handling without fracture as it issues from the press. I

The present invention has among its objects to enable the continuous-feed edge-gluing of strip elements to be carried out in a more rapid, facile and eflicient manner and with equipment which will require less space.

In the accompanying drawings which form part of the instant specification and are to be read in conjunction therewith and in which like numbers refer to like parts throughout the several views:

Fig. 1 is a partly fragmentary view in side elevation with parts in section of a typical and illustrative embodiment of continuous-feed, edge-joining apparatus in accordance with this invention suitable for carrying out the method of this invention;

there is provided a platform or table structure having at one end cyclic feeding mechanism for advancing a strip element treated with adhesive from one to the other of a pair of stations at the feed end of the platform.

The operating cycle of the feeding mechanism is preferably such as to provide a dwell or rest period between successive feeding periods thereby to enable the operator to position a fresh strip in the first or feed station following movement of the preceding strip to the second station of the pair. As each fresh strip, adhesively treated along one edge, is moved by the feeding mechanism from the first to the second station of the pair, it will move the preceding strip with a. firm pressure from the second station along and toward the other end of the platform or table. The addition of fresh adhesively treated strips may be continued until the assembly of strips has attained the desired length.

The several strips are treated with adhesive preferably prior to being placed in the feed station. so that a layer of adhesive will be interposed in the joint between successive strips and means are provided for electrostatically heating each joint for a predetermined period of time as the strips advance along the platform. To this end, the platform is provided intermediate its ends with one of a pair of electrodes in an ultra high frequency circuit, the other electrode being positioned in suitably spaced overlying relation thereto so as to provide a high frequency electrostatic field through which the strip assembly passes in transit along the platform. Under these conditions, the gluejoint between each pair of elements will be parallel or substantially parallel to the electrostatic field and the adhesive, which is preferably one of the so-called cold-setting liquid resin glues, for example, of the urea formaldehyde or phenolic type whose curing is accelerated by heat and the addition of a suitable catalyst, will be heated to the required temperature, set and caused to develop its full strength, substantially instantly. This is in marked contrast to the extended time required to obtain the same strength with conventional cold-press or hot-press edge-gluing pracv 3 tices. Because of the rapidity ,with which the heating is accomplished, the electrostatic field may be relatively short with material saving in length of apparatus over the conventional continof a of cam followe 38 carried by the levers 20 and are suitably contoured so that in. a full revolution from the position shown in Fig. 1, the ram l2 will be caused to remain at rest for part of the revolution, will then be advanced to therlght to the'full limit of its stroke and then be returned to its starting positionby the spring means 28;

height of the expansible inter-electrode passage,

a greater pressure will be required to overcome the frictional resistance offered by the electrodes and hence each strip element may be made to exert a greater pressure on its preceding ele- F ment. At the same time, the pressure between successive elements will be maintained at the de sired level during heating of the joint and until, the joint issues from the inter-electrode passageway.

It will be understood that the foregoing general description and the following detailed de-- smooth, table-like top surface 'H carries at one end a ram is overlying the top surface H. The front or working face is of the ram I2 is preferably planar and normal to the top surface ll so as to engage uniformly a work piece is and is preferably coextensive or substantially coextensive inwidth with the top surface ii.- A narrow footing It at the front of the ram slidably engages the top surface it of the platforrmthe ram being spaced from the surface rearwardly of the footing to minimize friction. At the back of the ram is a rod 86 which traverses the ram interiorly transversely of the platform. The rod i6 extends at its ends from either side of the ram into apair of slotted guide members I'I, one at each side of the platform, each having a slot i8 therein for the purpose provided. The guide members i! are anchored in any suitable fashion to the platform It as to which they and the slots is extend longitudinally so as to confine the, ram It to a limited longitudinal path of movement along the surface If.

' A pair of cam operated levers 20, one at each side of the platform ID are carried by a shaft 24 to which they are attached at either end by means of a pair of hubs 2| iournalled in a pair of bearing members 22 in turn carried by a pair of platform legs 23, one at each side of the platform.

The respective levers are provided at the top with a slot 25, the rod it being lodged at opposite ends in the respective slots. Spring means 26 provided at the bottom of each lever normally yieldably oppose clockwise movement thereof, as viewed in Fig.1. 1

A pair of cam members 30, one at each side of the platform, are carried by a shaft II to which they are attached at either end, the shaft 8| in turn being journalled adjacent its ends in a pair of bearings 32 secured to frame members 33 o the platform supporting structure.

A pulley 34 fixed to the shaft 3| is adapted to be driven by means of a suitable prime mover (not shown) to which the pulley is connected as by means of a belt 3!.

The cam members respectively engage one A pair of high frequency sheet metal, electrodes 40 and 4| are positioned intermediate the platform ends so as to receive therebetween the strip elements as they are successively advanced by the cyclical operation of the ram I2. The electrodes are connected in suitable fashion in an ultra high frequency electrical circuit powered by a suitable high frequency generator 42 diagrammatically indicated in Fig. 1.

The electrodes 4|! and 4| are preferably substantially coextensive in width with the platform It so as to extend the full length of the joint'between successive stripelements passing therebetween. They extend lengthwisemf the platform a distance suflicient to provide the hes-- essary time element for the desired heating effeet, their length being thus dependent to a measurable extent upon the average rate of travel of the strip elements therebetween, as will be apparent to those skilled in the art.

The electrode 60 may be a coating of copper or other suitable electrode material applied to the platform surface II in which case the electrode portion may be insulated from the platform portions on either side thereof. Or the electrode maybe insulated from the platform i0 as whole in any suitable fashion. As here prefers ly embodied, the electrode 40 is set into the platform Iii so as to lie flush therewith, and offer no obstruction to movement of the strip elements l4 thereover. The platform Ill in such case is constructed of wood or a material having suitable insulating, i. e. dielectric properties.

The electrode is preferably a thin sheet of aluminum, copper or other suitable metal having aturned-up edge 43 providing with the platform ill a converging mouth facilitating the entry of the workpiece It there-into and means are provided for resiliently adjustably mounting the electrode dl in spaced relation to the plat- .form i6 and the platform electrode 40 so as to the springs 41 serving to urge the rails 44 towardsets of rods 45, as viewed in Fig. 1, passing through front and rear supporting structures 48 vertically adjustably mounted on the platform The guide rods 45 are eachprovided with a coil spring 41 concentric therewith and extending between the related structure 46 and rail 44,

the platform l0. Adjusting units 48 carried by the rods 45 and coacting with the related supporting structure 46 are provided for limiting the extent of downward movement of the rails 44 and hence provide a means for controlling the pressure exerted by. the electrode 4| on the strip elements [4. In order to accommodate strip elements of different thicknesses between the electrodes, means are provided for vertically adjustably mounting the respective supporting structures 46 on the platform 10, which means may be any suitable mechanical arrangement enabling vertical adjustment of the frameworks 46 as a unit. As here preferably embodied, studs 49 pass through Vertical slots 50 in the opposite side rails 5| of the respective structures 46, into releasable engagement with the platform In at either side thereof.

In the operation of the depicted embodiment of this invention, the operator places a work piece M on the platform l0 against the ram I2 while the latter is at rest in its retracted position. The front face, that is, the bonding faces, of each succeeding strip element may be coated at this time with adhesive. Preferably, however, treating of a strip element with adhesive is carried out beforehand in any suitable fashion. The work piece I4 is now advanced automatically by operation of the cams 30, into the space between the high frequency electrodes 40 and 4|, the inter-electrode space having been adjusted to the thickness of the strip element and the pressure exerted by the spring pressed holddown electrode 4| normal to the strip element [4 having been established by suitable adjustment of the adjusting nuts 48. The pressure established is preferably just sufficient to cause the succeeding strip element as it is advanced by the ram ill, to exert a firm pressure on the preceding element uniformly over the joint surface and to maintain this pressure as the ram retreats to the first or feeding position. Thus, as the strip elements are advanced into and along the passage between the electrodes 40 and 4| a firm pressure will be exerted and maintained between each pair of electrodes at the bonding surface until the strip .elements exist from the inter-electrode passage. During the intermittent advance of the successive strip elements along the inter-electrode passage, an ultra-high frequency electrostatic field is maintained between the electrodes by means of the high frequency generator. This field is of sufficient intensity, considering voltage, frequency and capacitance, to heat the adhesive in each joint to a setting temperature and to develop substantially the maximum strength of the adhesive during the relatively short transit period of each joint as it advances in intermittent fashion along the passage. Because of the firm pressure maintained at the joint during transit and the preferential heating of the adhesive because of its high dielectric constant, the elements are firmly bonded to each other and the adhesive substantially full set in a very short space of time. The elements issue from between the electrodes as a continuous ribbon or panel structure such, for example, as is depicted in, Fig. 4. This structure may be cut to any desired length and since full setting of the adhesive is accomplished or substantially accomplished within the limits of the relatively short electrodes 40 and 4|, the device lends itself to use in places of limited floor space in which the conventional edge-gluing apparatus could not be employed.

It will be understood that apparatus of the nature aforesaid lends itself readily to the edgejoining of strip elements of different size. In general, wooden boards or other strip elements of a thickness in the range A" to 2", a width in the range 3" to 8" and any suitable length commensurate with the width of the electrodes, are representative ,of strip elements suitable as raw material for the production of unitary panel structures in accordance with thepresent invention. Obviously elements different in length and/or width, where thickness is the same, may be employed. With electrodes in the order of one foot in length, that is, in the direction of motion of the strip elements, satisfactory edge joining of such strip elements may be attained when employing a frequency of, for example, in the order of two (2) megacycles, a voltage of from 2000 to 3000 volts and a power input in the order of one (1) kilowatt to the electrodes. A transit time of around fifteen 5) seconds will generally be found more than sufiicient under these conditions to develop the maximum strength of the adhesive without noticeable heating of the wood. A materially great increase in production rate is thus made possible.

Instead of employing a pair of electrodes such as the electrodes 4|) and 4| of Fig. l, the upper electrode may consist of a strip 52 of sheet metal, Fig. 5, say A" or thick. One such strip is laid as shown over each "glue-joint 53 as it is made and passes through the machine. In such case. electrical contact is made with the top of each electrode strip 52 by means of a metal bar in the nature of a "hold down, or a series of such slidably engaging the electrodes as they pass therebeneath. The electrostatic field is set up between the strip electrodes and a table electrode as previously described along which the boards advance and which forms the lower electrode as they are pushed along by strokes of the ram. Such sparking as may occur as the strip contacts the hold down metal bar in its skid form, will have no deleterious effect on the Wood or glue joint. Preferably each strip electrode 52 is provided with short teeth prongs 54 normal to and projecting therefrom, these prongs or pin points being adapted to be pressed into the wood at either side of the glue line to prevent slipping of the electrode on the wood as the strip elements are advanced beneath the "hold down skids. Alternatively the electrodes may be provided with a frictional under surface for engaging the wood and preventing slippage on the wood.

The invention in its broader aspects is not limited to the specific steps and procedures and mechanisms shown and/or described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. Apparatus for continuous-feed, edge-glufng of strip elements comprising in comb nation a feed-table; a metal electrode in the table top; a flexible metal electrode overlying said table electrode; a framework carried by said table in vertically adjustable relation thereto; a plurality of members individually, independently supporting said flexible electrode from said framework in vertically adjustable relation thereto; spring members for yieldably opposing upward movement of said supporting members; means for advancing said strip elements along said table slidably between and along said electrodes in firm engagement with a preceding element; and, means for establishing a high-frequency electrostatic field between said electrodes.

2. Apparatus for continuous-feed, edge-gluing of strip elements comprising in combination a table electrode for slidably supporting said elements; means for advancing said elements sllccessively along said table electrode in firm en- 7 gagement with a preceding element; a flexible sheet metal electrode for slidably engaging the top surface of said elements; a plurality of rail members substantially paralleling the path of movement of said elements in spaced relation to each other and secured to the top surface of said flexible electrode; a framework vertically adjustably carried by said table; rod members extending upwardly from each end of the respective rail members into sliding engagement with said framework; spring means interposed between said framework and said rail members for yieldably resistin upward movement of said rail members;

means connected to said rod members for adjusting the spring tension; and, means for establishing a high-frequency electrostatic field between said electrodes.

3. Apparatus for continuous feed edge-gluing of strip elements comprising in combination a flat rigid table support for the Wake pair of high frequency plate electrodes, the lower electrode being embedded in said table support and being flush with the top of the table support, said electrodes each having a substantially plane surface portion in opposing substantially parallel spaced relation to the corresponding plane surfaced portion of the other to provide an elongated passageway through and along which strip elements to be edge glued are adapted to be advanced in edge-to-edge relationship with their upper and lower surfaces in sliding frictional engagement with said opposing plane surfaced portions; means for resiliently urging at least one of 8 said electrodes toward the other to obtain yielding frictional engagement between said strip elements and said electrode portions in transit through said passageway; intermittently operated feed means slidably supported on said table support in alignment with said passageway for advancing said strip elements successively into said passageway in firm engagement with a preceding element; and means for establishing a high-frequency electrostatic field between said electrodes.

PAUL H. BILHUBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 647,056 Ward Apr. 10, 1900 921,618 Murdock May 11, 1909 1,693,606 Jones Dec. 4, 1928 1,702,185 Weber Feb. 12, 1929 1,782,645 Chichester et al. Nov. 25, 19 0 1,875,056 Loetscher Aug. 30,19 2 2,231,457 Stephen Feb. 11, 19 1 2,288,269 Crandell June 30, 1 42 2,317,281 Linquist Apr. 20, 1943 2,324,068 Crandell July 13, 1943 FOREIGN PATENTS Number Country Date 509,377 Germany Jan. 9, 1927 

